Vulnerability-Lookup

GHSA-9QR7-MMM2-9F2R

Vulnerability from github – Published: 2026-09-29 18:31 – Updated: 2026-09-29 18:31

Details

Issue summary: SM2 signature generation uses non-constant-time arithmetic on secret values, forming a timing side-channel.

Impact summary: An attacker able to measure SM2 signing times may learn information about the per-signature secret nonce, which over many signatures can, via a lattice / Hidden Number Problem attack, lead to recovery of the private key.

CWE: CWE-208: Observable Timing Discrepancy

Description: SM2 signature generation computes the signature value using variable-time BIGNUM operations on the secret nonce and the private key, so the time taken to produce an SM2 signature depends on these secret values, forming a timing side-channel.

Applications performing SM2 signature generation are affected on all platforms.

FIPS Impact: no SM2 is not a FIPS algorithm.

Severity

3.7 (Low)


                  
                    CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

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{
  "affected": [],
  "aliases": [
    "CVE-2026-77696"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-208"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-29T16:17:11Z",
    "severity": "LOW"
  },
  "details": "Issue summary: SM2 signature generation uses non-constant-time arithmetic\non secret values, forming a timing side-channel.\n\nImpact summary: An attacker able to measure SM2 signing times may learn\ninformation about the per-signature secret nonce, which over many signatures\ncan, via a lattice / Hidden Number Problem attack, lead to recovery of the\nprivate key.\n\nCWE: CWE-208: Observable Timing Discrepancy\n\nDescription: SM2 signature generation computes the signature value using\nvariable-time BIGNUM operations on the secret nonce and the private key, so\nthe time taken to produce an SM2 signature depends on these secret values,\nforming a timing side-channel.\n\nApplications performing SM2 signature generation are affected on all\nplatforms.\n\nFIPS Impact: no\nSM2 is not a FIPS algorithm.",
  "id": "GHSA-9qr7-mmm2-9f2r",
  "modified": "2026-09-29T18:31:44Z",
  "published": "2026-09-29T18:31:44Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-77696"
    },
    {
      "type": "WEB",
      "url": "https://github.com/openssl/openssl/commit/1c4aed808a7aea32d2d013049c2e0d9fef164fc9"
    },
    {
      "type": "WEB",
      "url": "https://github.com/openssl/openssl/commit/20b20628d39b2dcc4677194bd68c7c060fa598cb"
    },
    {
      "type": "WEB",
      "url": "https://github.com/openssl/openssl/commit/419f5cb519721dceed393dbc524d79e487c72e64"
    },
    {
      "type": "WEB",
      "url": "https://github.com/openssl/openssl/commit/6b90445a56b99a328ac1feba058abf976504f440"
    },
    {
      "type": "WEB",
      "url": "https://openssl-library.org/news/secadv/20260929.txt"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-77696 (GCVE-0-2026-77696)

Vulnerability from cvelistv5 – Published: 2026-09-29 15:32 – Updated: 2026-09-29 16:51

Title

Timing Side-Channel in SM2 Signature Generation

Summary

Issue summary: SM2 signature generation uses non-constant-time arithmetic on secret values, forming a timing side-channel. Impact summary: An attacker able to measure SM2 signing times may learn information about the per-signature secret nonce, which over many signatures can, via a lattice / Hidden Number Problem attack, lead to recovery of the private key. CWE: CWE-208: Observable Timing Discrepancy Description: SM2 signature generation computes the signature value using variable-time BIGNUM operations on the secret nonce and the private key, so the time taken to produce an SM2 signature depends on these secret values, forming a timing side-channel. Applications performing SM2 signature generation are affected on all platforms. FIPS Impact: no SM2 is not a FIPS algorithm.

Severity

3.7 (Low)


                        
                          CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-29 16:51 UTC

CWE

CWE-208 - Observable Timing Discrepancy

Assigner

openssl mitre root Scorecard

References

5 references

URL	Tags
https://openssl-library.org/news/secadv/20260929.txt	vendor-advisory
https://github.com/openssl/openssl/commit/20b2062…	patch
https://github.com/openssl/openssl/commit/1c4aed8…	patch
https://github.com/openssl/openssl/commit/6b90445…	patch
https://github.com/openssl/openssl/commit/419f5cb…	patch

Impacted products

1 product

Vendor	Product	Version
OpenSSL	OpenSSL	Affected: 4.0.0 , < 4.0.3 (semver) Affected: 3.6.0 , < 3.6.5 (semver) Affected: 3.5.0 , < 3.5.9 (semver) Affected: 3.4.0 , < 3.4.8 (semver) Affected: 3.0.0 , < 3.0.23 (semver) Affected: 1.1.1 , < 1.1.1zj (custom)

Date Public

2026-09-29 14:21

Credits

Vladimir Tokarev Igor Ustinov Viktor Dukhovni

Show details on NVD website

JSON

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              "attackComplexity": "HIGH",
              "attackVector": "NETWORK",
              "availabilityImpact": "NONE",
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              "baseSeverity": "LOW",
              "confidentialityImpact": "LOW",
              "integrityImpact": "NONE",
              "privilegesRequired": "NONE",
              "scope": "UNCHANGED",
              "userInteraction": "NONE",
              "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N",
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                "id": "CVE-2026-77696",
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          "shortName": "CISA-ADP"
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          "vendor": "OpenSSL",
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              "status": "affected",
              "version": "4.0.0",
              "versionType": "semver"
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              "lessThan": "3.6.5",
              "status": "affected",
              "version": "3.6.0",
              "versionType": "semver"
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Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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GHSA-9QR7-MMM2-9F2R

CVE-2026-77696 (GCVE-0-2026-77696)

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